It is well-known that a vehicle includes various electric devices, such as interior lights and electric switches. These electric devices are connected with a power source or a controlling device via wiring. The wiring is usually concealed underneath interior decoration panel of a vehicle, for example, disposed between a vehicle floor and a carpet adjacent to the vehicle door so as to be invisible and thus providing good appearance.
In the conventional techniques, however, the wiring is usually laid directly between a vehicle's floor and a carpet near the vehicle doors. Thus, the carpet above the wiring may collapse due to lack of support when a passenger opens the door, touches or presses on a piece of carpet above the wiring. Further, since the wiring has no firmed structure, the wiring may become loose or shaking when in use and gets worn when departing from the designed position.